JL Wilson defends polygamy: http://independentcountry.blogspot.com/2006/08/defending-polygamy.html
I agree with him. To my way of thinking, central planning doesn’t work for family structure any more than it does for other things. Central planners can’t know the circumstances of individuals and households as well as those individuals and cannot possibly come up with an approved family form that works well for everyone.
In a free society, folks might organize themselves in households and families in a variety of ways. These would be strategic and account for the unique circumstances of the individuals involved far better than any regime devised by legislators. In time, some household and family arrangements might become more prevalent than others, but this does not mean that these should be privileged over other forms by the state.
Legislators who seek to preserve the family in some particular form through central planning are socialists plain and simple.